The subject matter of the present invention relates to perforating apparatus, and more particularly, to an apparatus for arming, testing and sequentially firing a plurality of perforating apparatus.
A perforating apparatus includes a plurality of charges, each of which will successively detonate when a detonation wave propagates along a detonating cord connected to the charge. The detonation wave originates from a booster which is adapted to receive an electrical current signal from an electrical conductor and which generates the detonation wave for propagation along the detonating cord. The electrical current signal is sometimes received by the booster when a switch closes thereby allowing the electrical correct to energize the booster. For example, U.S. Pat. No. 4,208,966 to Hart discloses a perforating system whereby a switch, when actuated, allows the electrical current signal to energize a booster for detonating one of the plurality of charges; however, the actuation of the switch also actuates another switch which successively drops one of a plurality of zener diodes from a circuit. In Hart, as the zener diodes successively drop out of the circuit in synchronism with the detonation of the plurality of charges, the identity of each detonated charge may be identified by the voltage present in the series connected zener diode circuit. However, in Hart, the actuation of the first aforementioned switch for detonating a first charge of the plurality of charges fails to enable the subsequent actuation of the switch in the perforating system, or the subsequent actuation of another switch in another perforating system, for detonating a second charge of the plurality; furthermore, no provision is made for taking appropriate compensatory action when the first aforementioned switch fails to actuate and thereby detonate the first charge of the plurality of charges. Finally, no provision is made for housing the system of Hart in a manner which provides a safe-arm feature.